If you answered yes to both of the above two questions, this offer features uncommonly generous exchange rates, especially if you're an elite member of US Airways' program or have their credit card. And if you have Starwood Preferred Guest points, the deal is better still.

Starwood famously adds a 5,000-mile bonus for transfers of 20,000 miles, so combining that with the US Airways bonus could generate as many as 43,750 US Airways miles in exchange for 20,000 Starwood points.

Reader Reality Check

Ultimately, the value of this promotion turns on the value of US Airways miles. How much are US Airways miles worth to you? More or less than miles in other airline programs?